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<FONT color="green">001</FONT>    // Copyright (c) 2011, Mike Samuel<a name="line.1"></a>
<FONT color="green">002</FONT>    // All rights reserved.<a name="line.2"></a>
<FONT color="green">003</FONT>    //<a name="line.3"></a>
<FONT color="green">004</FONT>    // Redistribution and use in source and binary forms, with or without<a name="line.4"></a>
<FONT color="green">005</FONT>    // modification, are permitted provided that the following conditions<a name="line.5"></a>
<FONT color="green">006</FONT>    // are met:<a name="line.6"></a>
<FONT color="green">007</FONT>    //<a name="line.7"></a>
<FONT color="green">008</FONT>    // Redistributions of source code must retain the above copyright<a name="line.8"></a>
<FONT color="green">009</FONT>    // notice, this list of conditions and the following disclaimer.<a name="line.9"></a>
<FONT color="green">010</FONT>    // Redistributions in binary form must reproduce the above copyright<a name="line.10"></a>
<FONT color="green">011</FONT>    // notice, this list of conditions and the following disclaimer in the<a name="line.11"></a>
<FONT color="green">012</FONT>    // documentation and/or other materials provided with the distribution.<a name="line.12"></a>
<FONT color="green">013</FONT>    // Neither the name of the OWASP nor the names of its contributors may<a name="line.13"></a>
<FONT color="green">014</FONT>    // be used to endorse or promote products derived from this software<a name="line.14"></a>
<FONT color="green">015</FONT>    // without specific prior written permission.<a name="line.15"></a>
<FONT color="green">016</FONT>    // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS<a name="line.16"></a>
<FONT color="green">017</FONT>    // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT<a name="line.17"></a>
<FONT color="green">018</FONT>    // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS<a name="line.18"></a>
<FONT color="green">019</FONT>    // FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE<a name="line.19"></a>
<FONT color="green">020</FONT>    // COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,<a name="line.20"></a>
<FONT color="green">021</FONT>    // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,<a name="line.21"></a>
<FONT color="green">022</FONT>    // BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;<a name="line.22"></a>
<FONT color="green">023</FONT>    // LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER<a name="line.23"></a>
<FONT color="green">024</FONT>    // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT<a name="line.24"></a>
<FONT color="green">025</FONT>    // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN<a name="line.25"></a>
<FONT color="green">026</FONT>    // ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE<a name="line.26"></a>
<FONT color="green">027</FONT>    // POSSIBILITY OF SUCH DAMAGE.<a name="line.27"></a>
<FONT color="green">028</FONT>    <a name="line.28"></a>
<FONT color="green">029</FONT>    package org.owasp.html.examples;<a name="line.29"></a>
<FONT color="green">030</FONT>    <a name="line.30"></a>
<FONT color="green">031</FONT>    import java.io.IOException;<a name="line.31"></a>
<FONT color="green">032</FONT>    import java.io.InputStreamReader;<a name="line.32"></a>
<FONT color="green">033</FONT>    import java.util.regex.Pattern;<a name="line.33"></a>
<FONT color="green">034</FONT>    <a name="line.34"></a>
<FONT color="green">035</FONT>    import org.owasp.html.Handler;<a name="line.35"></a>
<FONT color="green">036</FONT>    import org.owasp.html.HtmlPolicyBuilder;<a name="line.36"></a>
<FONT color="green">037</FONT>    import org.owasp.html.HtmlSanitizer;<a name="line.37"></a>
<FONT color="green">038</FONT>    import org.owasp.html.HtmlStreamEventReceiver;<a name="line.38"></a>
<FONT color="green">039</FONT>    import org.owasp.html.HtmlStreamRenderer;<a name="line.39"></a>
<FONT color="green">040</FONT>    <a name="line.40"></a>
<FONT color="green">041</FONT>    import com.google.common.base.Charsets;<a name="line.41"></a>
<FONT color="green">042</FONT>    import com.google.common.base.Function;<a name="line.42"></a>
<FONT color="green">043</FONT>    import com.google.common.base.Throwables;<a name="line.43"></a>
<FONT color="green">044</FONT>    import com.google.common.io.CharStreams;<a name="line.44"></a>
<FONT color="green">045</FONT>    <a name="line.45"></a>
<FONT color="green">046</FONT>    /**<a name="line.46"></a>
<FONT color="green">047</FONT>     * Based on the<a name="line.47"></a>
<FONT color="green">048</FONT>     * &lt;a href="http://www.owasp.org/index.php/Category:OWASP_AntiSamy_Project#Stage_2_-_Choosing_a_base_policy_file"&gt;AntiSamy Slashdot example&lt;/a&gt;.<a name="line.48"></a>
<FONT color="green">049</FONT>     * &lt;blockquote&gt;<a name="line.49"></a>
<FONT color="green">050</FONT>     * Slashdot (http://www.slashdot.org/) is a techie news site that allows users<a name="line.50"></a>
<FONT color="green">051</FONT>     * to respond anonymously to news posts with very limited HTML markup. Now<a name="line.51"></a>
<FONT color="green">052</FONT>     * Slashdot is not only one of the coolest sites around, it's also one that's<a name="line.52"></a>
<FONT color="green">053</FONT>     * been subject to many different successful attacks. Even more unfortunate is<a name="line.53"></a>
<FONT color="green">054</FONT>     * the fact that most of the attacks led users to the infamous goatse.cx picture<a name="line.54"></a>
<FONT color="green">055</FONT>     * (please don't go look it up). The rules for Slashdot are fairly strict: users<a name="line.55"></a>
<FONT color="green">056</FONT>     * can only submit the following HTML tags and no CSS: {@code &lt;b&gt;}, {@code &lt;u&gt;},<a name="line.56"></a>
<FONT color="green">057</FONT>     * {@code &lt;i&gt;}, {@code &lt;a&gt;}, {@code &lt;blockquote&gt;}.<a name="line.57"></a>
<FONT color="green">058</FONT>     * &lt;br&gt;<a name="line.58"></a>
<FONT color="green">059</FONT>     * Accordingly, we've built a policy file that allows fairly similar<a name="line.59"></a>
<FONT color="green">060</FONT>     * functionality. All text-formatting tags that operate directly on the font,<a name="line.60"></a>
<FONT color="green">061</FONT>     * color or emphasis have been allowed.<a name="line.61"></a>
<FONT color="green">062</FONT>     * &lt;/blockquote&gt;<a name="line.62"></a>
<FONT color="green">063</FONT>     */<a name="line.63"></a>
<FONT color="green">064</FONT>    public class SlashdotPolicyExample {<a name="line.64"></a>
<FONT color="green">065</FONT>    <a name="line.65"></a>
<FONT color="green">066</FONT>      /** A policy definition that matches the minimal HTML that Slashdot allows. */<a name="line.66"></a>
<FONT color="green">067</FONT>      public static final Function&lt;HtmlStreamEventReceiver, HtmlSanitizer.Policy&gt;<a name="line.67"></a>
<FONT color="green">068</FONT>          POLICY_DEFINITION = new HtmlPolicyBuilder()<a name="line.68"></a>
<FONT color="green">069</FONT>              .allowStandardUrlProtocols()<a name="line.69"></a>
<FONT color="green">070</FONT>              // Allow title="..." on any element.<a name="line.70"></a>
<FONT color="green">071</FONT>              .allowAttributes("title").globally()<a name="line.71"></a>
<FONT color="green">072</FONT>              // Allow href="..." on &lt;a&gt; elements.<a name="line.72"></a>
<FONT color="green">073</FONT>              .allowAttributes("href").onElements("a")<a name="line.73"></a>
<FONT color="green">074</FONT>              // Defeat link spammers.<a name="line.74"></a>
<FONT color="green">075</FONT>              .requireRelNofollowOnLinks()<a name="line.75"></a>
<FONT color="green">076</FONT>              // Allow lang= with an alphabetic value on any element.<a name="line.76"></a>
<FONT color="green">077</FONT>              .allowAttributes("lang").matching(Pattern.compile("[a-zA-Z]{2,20}"))<a name="line.77"></a>
<FONT color="green">078</FONT>                  .globally()<a name="line.78"></a>
<FONT color="green">079</FONT>              // The align attribute on &lt;p&gt; elements can have any value below.<a name="line.79"></a>
<FONT color="green">080</FONT>              .allowAttributes("align")<a name="line.80"></a>
<FONT color="green">081</FONT>                  .matching(true, "center", "left", "right", "justify", "char")<a name="line.81"></a>
<FONT color="green">082</FONT>                  .onElements("p")<a name="line.82"></a>
<FONT color="green">083</FONT>              // These elements are allowed.<a name="line.83"></a>
<FONT color="green">084</FONT>              .allowElements(<a name="line.84"></a>
<FONT color="green">085</FONT>                  "a", "p", "div", "i", "b", "em", "blockquote", "tt", "strong",<a name="line.85"></a>
<FONT color="green">086</FONT>                  "br", "ul", "ol", "li")<a name="line.86"></a>
<FONT color="green">087</FONT>              // Custom slashdot tags.<a name="line.87"></a>
<FONT color="green">088</FONT>              // These could be rewritten in the sanitizer using an ElementPolicy.<a name="line.88"></a>
<FONT color="green">089</FONT>              .allowElements("quote", "ecode")<a name="line.89"></a>
<FONT color="green">090</FONT>              .toFactory();<a name="line.90"></a>
<FONT color="green">091</FONT>    <a name="line.91"></a>
<FONT color="green">092</FONT>      public static void main(String[] args) throws IOException {<a name="line.92"></a>
<FONT color="green">093</FONT>        if (args.length != 0) {<a name="line.93"></a>
<FONT color="green">094</FONT>          System.err.println("Reads from STDIN and writes to STDOUT");<a name="line.94"></a>
<FONT color="green">095</FONT>          System.exit(-1);<a name="line.95"></a>
<FONT color="green">096</FONT>        }<a name="line.96"></a>
<FONT color="green">097</FONT>        System.err.println("[Reading from STDIN]");<a name="line.97"></a>
<FONT color="green">098</FONT>        // Fetch the HTML to sanitize.<a name="line.98"></a>
<FONT color="green">099</FONT>        String html = CharStreams.toString(<a name="line.99"></a>
<FONT color="green">100</FONT>            new InputStreamReader(System.in, Charsets.UTF_8));<a name="line.100"></a>
<FONT color="green">101</FONT>        // Set up an output channel to receive the sanitized HTML.<a name="line.101"></a>
<FONT color="green">102</FONT>        HtmlStreamRenderer renderer = HtmlStreamRenderer.create(<a name="line.102"></a>
<FONT color="green">103</FONT>            System.out,<a name="line.103"></a>
<FONT color="green">104</FONT>            // Receives notifications on a failure to write to the output.<a name="line.104"></a>
<FONT color="green">105</FONT>            new Handler&lt;IOException&gt;() {<a name="line.105"></a>
<FONT color="green">106</FONT>              public void handle(IOException ex) {<a name="line.106"></a>
<FONT color="green">107</FONT>                Throwables.propagate(ex);  // System.out suppresses IOExceptions<a name="line.107"></a>
<FONT color="green">108</FONT>              }<a name="line.108"></a>
<FONT color="green">109</FONT>            },<a name="line.109"></a>
<FONT color="green">110</FONT>            // Our HTML parser is very lenient, but this receives notifications on<a name="line.110"></a>
<FONT color="green">111</FONT>            // truly bizarre inputs.<a name="line.111"></a>
<FONT color="green">112</FONT>            new Handler&lt;String&gt;() {<a name="line.112"></a>
<FONT color="green">113</FONT>              public void handle(String x) {<a name="line.113"></a>
<FONT color="green">114</FONT>                throw new AssertionError(x);<a name="line.114"></a>
<FONT color="green">115</FONT>              }<a name="line.115"></a>
<FONT color="green">116</FONT>            });<a name="line.116"></a>
<FONT color="green">117</FONT>        // Use the policy defined above to sanitize the HTML.<a name="line.117"></a>
<FONT color="green">118</FONT>        HtmlSanitizer.sanitize(html, POLICY_DEFINITION.apply(renderer));<a name="line.118"></a>
<FONT color="green">119</FONT>      }<a name="line.119"></a>
<FONT color="green">120</FONT>    }<a name="line.120"></a>




























































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